<!DOCTYPE html>
<html lang="zh_CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            border: red 10px solid;
            /* overflow: hidden; */
            float: left;
/*开启隐藏BFC的方式：
1.设置float
2.将元素设置为行内元素display
3.设置overfloat*/
/*设置overflow后，可以使父元素包含浮动的子元素*/
        }
        .box1{
            width: 50px;
            height: 50px;
            background-color: aquamarine;
            float: left;
        }
        .box3{
            width: 100px;
            height: 100px;
            background-color: orange;
            float: left;
        }
    </style>
</head>
<body>
    <div class="box">
        <div class="box1"></div>
        <div class="box3"></div>
    </div>
</body>
</html>